1. Field of the Invention
This invention relates to conveying systems with movable conveying belts for transporting discrete objects and material and, more particularly, to a sealing system for controlling migration of objects/materials off of the conveying belt transversely to a conveying direction.
2. Background Art
Conveying belts are used in a wide range of environments to transport materials, that are typically in a flowable form, and objects between spaced locations. A typical conveying section will have spaced rollers around which a conveying belt is trained so that an upwardly facing belt surface is situated to receive and move materials and objects as the belt is advanced. Virtually any type of object or material that can be supported by the upwardly facing surface on the conveying belt can be transported with such a system.
As one example, it is known to transport particulate material using such systems. Typically, the belt will be supported in a trough-shaped configuration for this purpose, as shown in exemplary U.S. Pat. No. 6,547,062. The angled, lateral edges of the belt function to funnel materials towards the center of the belt, whereas said material might otherwise tend to migrate laterally off of the belt.
To further confine lateral movement of the conveying materials, it is common to incorporate containment walls at the lateral sides of the belt. Commonly, a vertical gap will be maintained between these walls and the upwardly facing horizontal or angled belt surface regions to avoid binding therebetween during operation. To confine migration of material through this vertical gap and laterally off of the belt to the adjacent environment, it is known to use sealing assemblies with edges, made from a resilient material, that will engage, and conform to accommodate dimensional and configurational variations in, belt surfaces during operation of the belt.
An exemplary sealing assembly is shown in U.S. Pat. No. 5,016,747. The sealing assembly shown in this patent consists of a primary sealing subassembly and a secondary sealing subassembly. The primary sealing subassembly is responsible for substantially blocking the vertical gap between the containment wall and the belt. The secondary sealing subassembly is arranged laterally outside the containment wall and confines any material that finds its way laterally outwardly through the gap between the primary sealing subassembly, and belt. This condition is likely to occur since it is specifically taught in this patent that a gap be maintained between the primary sealing subassembly and the conveying belt.
Each time the sealing assembly, or any portion thereof, must be repaired or replaced, an entire line may have to be shut down, even though the affected region constitutes only a small portion of the overall system. This may have a significant economic impact in terms of the operational interruption as well as its necessitating having on hand available parts and competent labor to effect repairs. Thus, designers of these sealing assemblies strive towards a design that will have an extended life. This objective generally leads designers to engineer sealing assemblies with relatively thick components.
With the sealing assembly made from resilient materials, at a certain thickness, it is difficult to shape and install the sealing assembly on site. With such designs, the primary sealing subassembly and secondary sealing subassembly may remain at all times generally at a fixed angle with respect to each other. The separate lengths of the sealing assembly may thus have a substantial effective volume as a result of which they take up valuable space in facilities and may account for high shipping costs. This configuration may also make handling difficult, as during transportation, installation, and maintenance thereof. Still further, since the sealing components are relatively rigid by reason of their thickness, a gap may have to be maintained between the primary sealing subassembly and belt to avoid binding during operation. This gap affords an egress for particularly small particles.
Alternatively, the primary and secondary sealing subassembly may be joined in a manner that they are collapsible towards each other for storage and handling and repositionable angularly relative to each other during assembly. A single molded piece may have to be made thin enough to hinge and thereby make this relative movement possible. This may create a weakening, as result of which the sealing assembly is prone to failure. Alternatively, a thicker hinge region may inhibit relative movement of the sections, whereupon there is a significant amount of distortion that is caused during system setup. This may compromise the integrity of the seal afforded by the primary and/or secondary sealing subassemblies.
To address the above-described handling and storage problems, it is known to make the sealing assemblies so that at least a part of the secondary sealing subassembly is separable from the primary sealing subassembly. This allows compaction of the sealing assemblies for storage and transportation and also gives more flexibility as to designs that might otherwise be dimensionally cumbersome. However, this type of system necessitates potentially time consuming assembly steps and may require a relatively high level of skill to accomplish this, and subsequent repairs, at the installation site.
With all of the above designs, improper installations may lead to loss of materials from the conveying system to the outside environment and potentially premature failure of a part or all of a sealing assembly. In a worse case, the improper installation may interfere with the basic conveying system function.
The industry continues to seek out sealing assembly designs that are capable of being consistently installed and maintained in a relatively economical manner, that will have a long life, that will effectively perform a sealing function, and that are configured for convenient handling, storage, and transportation.